It would make sense if by December 2016 we get a Season 2 Annoucement(That will be set for the Fall 2017).
By 2017 Murata should be on the climax of the MA arc.
That arc in total in Original was as long as all arcs before put together. I would say 2017 end is most realistic if we do not want Murata to overwork himself and pay for it with health.
I wonder if next season which most likely will have Garou at the center, will have 12 epi, or if they will increase the cap.
Different from Boros which just appear out of nowhere and become a major threat, Garou fleshes out much more through the story till the climax, besides that, there is the Monster Association, and if they want to adapt Murata's extra content, i don't know if 12 episodes will be enough to wrap the entire story.
I would say they would need around 40 episodes with good pace. This season was quite fast, maybe even too fast paces at some episodes imo.